1. Field of the Invention
The present invention relates to a lens barrel attached to a camera or the like and, more particularly, to a lens barrel that has a plurality of cylindrical members configured to advance and retreat rectilinearly in parallel with the direction of an optical axis and a plurality of actuators electrically driven within the lens barrel.
2. Description of the Related Art
In recent years, zoom lens barrels used in digital cameras and the like have shown a tendency that a focal-length ratio (what is called a zoom magnification) is large, and thus, a moving-distance (more particularly, a moving-distance towards an object side or a moving-distance towards an imaging plane side) of a photographing lens in a lens barrel used in a camera is large. On the other hand, from a viewpoint of enhancing portability of cameras, there have been demands for reduction in size of cameras and lens barrels. In other words, a lens barrel has been required, which is adapted such that when electric-power is on, the moving-distance of the photographing lens is large, and when electric-power is off, the lens barrel is compactly fit into the camera.
As the camera enhances its functions, the lens barrel has come to be provided with not only a stop mechanism and a shutter mechanism but a novel mechanism typified by a new mechanism (such as a camera-shake correction mechanism).
In addition, in order to achieve function enhancement of the camera, the lens barrel has many actuators for driving the stop mechanism, the shutter mechanism, and the camera-shake mechanism, which are electrically connected to a system controller, and many detection elements for controlling various mechanisms.
In such a lens barrel, lead wires and a plurality of flexible printed circuit boards are used to electrically connect the system controller to the actuators and the detection elements provided therein.
Hitherto, a lens barrel using two flexible printed circuit boards has been proposed. The lens barrel has a first flexible printed circuit board for connecting a driving source of each of an antivibration driving mechanism and a shutter driving mechanism to an electrical control means provided outside the barrel. In addition, the lens barrel has a second flexible printed circuit board for connecting a driving source of a focusing mechanism to the electrical control means provided outside the barrel. The first flexible printed circuit board and the second flexible printed circuit board are arranged to be wired around within the lens barrel in a two-ply state. For example, Japanese Patent Application Laid-Open No. 07-159668 discusses that a soldered part of the first flexible printed circuit board is connected to an electric component, such as a motor arranged in the lens barrel, perpendicular to an optical axis by soldering.
For example, Japanese Patent Application Laid-Open No. 2008-65179 has proposed and discussed a lens barrel in which an image stabilization (IS) flexible printed circuit board and a shutter (SH) flexible printed circuit board are wired around in a two-ply state. In the case of the lens barrel, the IS flexible printed circuit board and the SH flexible printed circuit board are drawn out of the lens barrel in a two-ply state and connected to a control printed circuit board, on which a central processing unit (CPU) is mounted, in a digital camera.
If the above lens barrel is configured such that the flexible printed circuit boards are wired in a two-ply state, a reaction force at bending of the flexible printed circuit boards is large (what is called high resilience). Because the two-ply flexible printed circuit board is high in resilience, an unwanted force acts upon the actuator, to which the flexible printed circuit boards are attached, and the like. Thus, operations of the actuators and the lens barrel are destabilized.
In addition, as described above, in the configuration in which the soldered part on the flexible printed circuit board is arranged perpendicular to the optical axis, a size of the lens barrel becomes large in the direction of a diameter.
If a digital camera is configured by drawing the two-ply flexible printed circuit board out of the lens barrel and connecting the two-ply flexible printed circuit board to the control printed circuit board of the digital camera, a plurality of long and large flexible printed circuit boards should be used. Accordingly, the material cost of the flexible print circuit boards is high. This causes increase in the cost of the lens barrel.